ACL fixation pin

ABSTRACT

A pin ( 20 ) is provided for securing a replacement ligament ( 24 ) inside a tunnel ( 10 ) of a receptor bone ( 36 ). A threaded section ( 30 ) of the pin ( 20 ) engages and anchors the pin ( 20 ) in the receptor bone ( 36 ). A first taper ( 26 ) opposite the threaded section ( 30 ) is configured to enter a drilled hole ( 14 ) which is transverse to the tunnel ( 10 ), capture a looped replacement ligament ( 24 ), and extend into the medial side ( 25 ) of the receptor bone ( 36 ). A second taper ( 28 ) urges the replacement ligament ( 24 ) against the wall ( 15 ) of the tunnel ( 10 ) and provides resistance when the second taper ( 28 ) contacts the medial side ( 25 ) of the bone ( 36 ), thus signaling that the pin ( 20 ) has been inserted to the proper depth. The body ( 21 ) of the pin ( 20 ) secures the looped replacement ligament ( 24 ) in the tunnel ( 10 ) and holds the replacement ligament ( 24 ) in contact with the wall ( 15 ) of the tunnel ( 10 ) to insure ingrowth.

CROSS-REFERENCES TO RELATED APPLICATIONS

[0001] This application is a divisional of U.S. application Ser. No.09/508,154, now U.S. Pat. No. 6,306,138, filed Mar. 7, 2000, which is aU.S. national application of international application serial No.PCT/US98/19931 filed Sep. 24, 1998, which claims priority to U.S.provisional applications serial Nos. 60/059,877 and 60/078,404 filedSep. 24, 1997, and Mar. 18, 1998, respectively.

BACKGROUND AND SUMMARY OF THE INVENTION

[0002] The present invention relates to the anchoring of ligamentreplacements or soft tissue in bone tunnels, and more particularly to across pin and a method of fixing the cross pin which facilitatessecuring a replacement graft inside a bone and that promotes healing ofthe graft inside the bone.

[0003] When a ligament such as an anterior cruciate ligament(hereinafter “ACL”) of a knee is damaged or torn, a replacement ligamentis often installed in the knee to reconstruct the natural ACL. Duringsuch reconstruction, with the knee bent appropriately, a tunnel istypically drilled through the anterior portion of the tibia upwardlythrough the tibial plateau and into the distal end of the femur toapproximate the natural position of the ACL, in accordance with wellknown surgical techniques. A bone-ligament-bone graft is then harvested,often from the patellar tendon following standard grafting techniques,all well known in the orthopaedic field. Typically, a wedge-shapedbone-ligament-bone graft is cut and contoured using a graft guide.

[0004] Various fixation methods are known in the orthopaedic field forsecuring a bone-ligament-bone graft within the tibia and femur so thatthe graft can heal. For example, it is known to use a pin installedtransversely to the bone tunnel to secure the replacement ligamentwithin the tunnel such as that shown in U.S. Pat. No. 5,397,356 entitled“Pin for Securing a Replacement Ligament to a Bone” to E. Marlowe Gobleand Jerry L. Lower. Also, methods for installing such a cross pin areshown in U.S. Pat. No. 5,139,520 entitled “Method for ACLReconstruction” to Thomas D. Rosenberg; U.S. Pat. No. 5,562,671 entitled“Ligament Replacement Cross Pinning Method” to E. Marlowe Goble andJerry L. Lower; and U.S. Pat. No. 5,350,380 entitled “Method forSecuring a Ligament Replacement in a Bone” to E. Marlowe Goble and JerryL. Lower. The devices and methods disclosed in these patents areincorporated herein by reference. These types of pins often operate byholding and forcing the bone block at the end of the replacementligament against the wall of the tunnel, essentially wedging the boneblock in place. In other known methods, sutures coupled to the graft areanchored to the bone using screws or washers. The replacement ligamentscan also be coupled directly to the bone using plates or washers inconjunction with a bone screw. Alternatively, the replacement ligamentcan be secured by interference screw fixation, as disclosed in U.S. Pat.No. 4,950,270 entitled “Cannulated Self-Tapping Bone Screw” to Jerald A.Bowman and Richard V. Zile.

[0005] Other materials which can be used as replacement ligamentsinclude the gracilis tendon, semitendinosus tendon, and small intestinesubmucosa (hereinafter “SIS). U.S. Pat. No. 4,902,508 entitled “TissueGraft Composition” to Stephen F. Badylak, et al.; U.S. Pat. No.5,281,422 entitled “Graft for Promoting Autogenous Tissue Growth” toStephen F. Badylak, et al.; and U.S. Pat. No. 5,611,969 entitled “LargeArea Submucosal Tissue Graft Constructs” to Umesh H. Patel, et al.describe harvesting and preparation of SIS grafts. The methods andmaterials disclosed in these patents are incorporated herein byreference. While these graft materials perform well, prior artprocedures for inserting and securing such material are time consuming.Also, in situations where previous reconstruction has been performed, anew femoral tunnel placed close to the previous tunnel may not allow forfixation methods such as interference screw fixation.

[0006] Replacement ligaments can be secured within the femoral tunnelwithout the use of a bone plug by looping the replacement ligament overa cross pin. A tendon threader, such as those described in U.S. Pat. No.5,266,075 entitled “Tendon Threader for Endosteal Ligament Mounting” toRon Clark and Raymond E. Olsen; and U.S. Pat. No. 5,601,562 entitled“Forked Insertion Tool and Method of Arthroscopic Surgery Using theSame” to Eugene M. Wolf and Richard D. Grafton, can be used to form aloop in the replacement ligament and to position the replacementligament within the femoral tunnel so that the loop may be captured bythe cross pin. The devices and methods disclosed in these patents areincorporated herein by reference.

[0007] Methods which use a cross pin to secure a looped replacementligament are effective, especially in situations in which there had beena previous reconstruction. Unfortunately, existing cross pins were notdesigned for this purpose. Generally, they were designed to wedge a boneblock into the medial wall of the bone tunnel. These pins were notdesigned to be inserted easily into a graft loop, and they were notdesigned to hold the graft material in contact with the femoral wall,which would insure better ingrowth.

[0008] The graft fixation method and cross pin of the present inventionprovide advantages over the prior fixation methods and pins. The pinincludes two tapered portions, a body, and a threaded portion. In theillustrated embodiment, the first tapered portion is long, relativelynarrow, has a gentle taper, and can be inserted easily through thetransversely drilled hole and into the graft insertion tool, where itcaptures the loop of the replacement ligament more easily than priorpins. The first tapered portion also inserts easily into the medial sideof the femur. Because the first tapered portion is relatively narrow, itmay eliminate the need for a guidewire during insertion of the pin.

[0009] In the illustrated embodiment, the second tapered portion issubstantially shorter and has a more severe taper than the first taperedportion. Also, as illustrated, the body portion is cylindrical, but bodyportions with other shapes may be acceptable. As the cross pin isinserted, the wider second tapered portion compresses the replacementligament against the wall of the femoral tunnel. The body of the crosspin then holds the replacement ligament against the wall. Thus, thepresent invention insures better ingrowth and provides a more securefixation technique than previously found. An additional advantage of thecurrent invention is that the second tapered portion provides resistancewhen it meets the medial wall of the femoral tunnel, thus signaling whenthe cross pin is fully seated. Another advantage of the current fixationmethod and pin is that rigid fixation afforded by the cross pin allowsthe patient immediately to bear weight and start range of motionexercises.

[0010] Also in the illustrated embodiment, when the cross pin is fullyseated, the threaded portion will be buried in the femur, and theproximal end of the cross pin will be flush with the lateral surface ofthe femur. However, a cross pin having a head which may protrude fromthe lateral surface of the femur is also within the scope of thisinvention. Such a head may aid in installation or may be useful forlater removal of the pin.

[0011] The present invention also includes a method for installing thecross pin. By using the illustrated method, a surgeon may insert thelooped replacement ligament into the femoral tunnel, capture the loopwith the cross pin with relative ease, and seat the cross pin at theappropriate depth. The method results in a replacement ligament which isheld securely in the femoral tunnel, in such a way as to insure rapidingrowth.

[0012] Additional objects, features, and advantages of the presentinvention will become apparent from the following description of apreferred embodiment exemplifying the best mode of carrying out theinvention as presently perceived.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013]FIG. 1 is a cross-sectional view of a femoral tunnel showing adrill pin extending through the femoral tunnel into the medial side ofthe femoral tunnel;

[0014]FIG. 2 is a view similar to FIG. 1 showing the drill pin in atransverse tunnel across the femoral tunnel and into the medial side,and showing a cross pin reamer inserted over the drill pin and extendingthrough the lateral side of the femoral tunnel;

[0015]FIG. 3 is a view similar to FIG. 2 after the drill pin and crosspin reamer are withdrawn from the transverse tunnel, a cross pinguidewire is inserted in the lateral side of the transverse tunnel, anda replacement ligament wrapped around a soft tissue tendon passer isinserted into the femoral tunnel;

[0016]FIG. 4 is a view similar to FIG. 3 after the tendon passer isremoved from the femoral tunnel and showing the cross pin guidewireextending completely through a cross pin (in cross-section), through thefemoral tunnel, through the replacement ligament looped over the crosspin, and into the medial side of the femoral tunnel;

[0017]FIG. 5 is a view similar to FIG. 4 showing a first tapered portionof the cross pin just being inserted into a medial side of the femoraltunnel;

[0018]FIG. 6 shows the cross pin beginning to occupy an increasingportion of the femoral tunnel;

[0019]FIG. 7 shows further insertion of the cross pin through thefemoral tunnel, such that a second tapered portion has entered thefemoral tunnel and the second tapered portion has begun to hold thereplacement ligament against the wall of the femoral tunnel;

[0020]FIG. 8 shows the cross pin at a position of maximum insertion andtendon compression where the second tapered portion on cross pin is incontact with the medial side of the femoral tunnel, and the body oncross pin compresses the replacement ligament securely against the wallof the femoral tunnel;

[0021]FIG. 9 is a side view of the cross pin and the cross pin guidewirein accordance with the present invention showing a proximal end of thecross pin having a threaded portion for securing the cross pin withinthe femur (not shown), two tapered portions, the first tapered portionbeing positioned at the distal end of the cross pin and proportioned anddesigned to slide within the tendon passer, through the loopedreplacement ligament, and into the medial side of the femoral tunnel,the second tapered portion of the cross pin being positioned adjacent tothe first tapered portion and proportioned and designed to begin theprocess of holding the replacement ligament against the wall of thefemoral tunnel and to provide resistance when it engages the medial sideof the femoral tunnel, and a body proportioned and designed to hold thereplacement ligament against the wall of the femoral tunnel for thepurpose of ingrowth;

[0022]FIG. 10 is a side view of an alternative embodiment of the crosspin showing a head adjacent to the threaded portion;

[0023]FIG. 11 is a view of a tibia and femur showing a reamer placedwithin the tibial tunnel and femoral tunnel, the reamer extending intothe cortex of the femur, a ratcheting cannula positioned through atunnel locator which is coupled to a cross pin guide, and a drill pinwhich is placed through the ratcheting cannula;

[0024]FIG. 12 is a view similar to FIG. 11 after the reamer has beenremoved from the femoral tunnel, showing the drill pin through theratcheting cannula after the drill pin has drilled through the femoraltunnel and into the medial side of the femur, the drill pin intersectingthe axis of the femoral tunnel; and

[0025]FIG. 13 is a view similar to FIG. 12 showing the cross pin overthe guide wire as the cross pin is about to be inserted into the femurand also showing the tendon passer holding the replacement ligament tobe inserted through the tibia and into the femoral tunnel.

DETAILED DESCRIPTION OF THE DRAWINGS

[0026] In accordance with the present invention, a cross pin fixationsystem is provided for ACL reconstruction. In the method of the presentinvention, as illustrated, replacement ligaments of semitendinosustendon, gracilis tendon, or SIS are used to replace the ACL. However, itis understood that other materials may be used as the replacementligament within the scope of the invention. A looped replacementligament 24 is inserted into the femoral tunnel 10. A cross pin 20secures the replacement ligament 24 by holding the replacement ligament24 against the wall 15 of a femoral tunnel 10. See FIG. 10. It will beappreciated that this holding action occurs in the illustratedembodiment by wedging and compressing the replacement ligaments againstthe wall of the femoral tunnel 10. The improved fixation method alsosecures the replacement ligament 24 by looping the replacement ligament24 around the cross pin 20 itself. Thus, the replacement ligament 24 issecured over and around the cross pin 20 which is placed across thefemoral tunnel 10 perpendicular to its axis. While the illustratedembodiment details a cross pin fixation method for ACL reconstruction,the pin and method of the present invention also may be used for othertypes of reconstruction. The graft fixation system of the presentinvention provides accurate and reproducible placement of the cross pin20 while providing secure rigid fixation of the replacement ligament 24.

[0027] The fixation system of the present invention briefly includes thefollowing steps and devices:

[0028] The present method for replacing the ACL begins with drilling atunnel 11 through the tibia 34. Before drilling begins, a tibial guidepin (not shown) is inserted from the anteromedial tibia and exits on thetibial plateau. This tibial guide pin is then over-drilled with areamer. A back cutting burr (not shown) then smooths the tunnel rim (notshown) of debris. The knee is flexed 90 to 110 degrees, and a femoralaimer (not shown) is used to locate a desired position of the femoraltunnel 10. Once the desired position has been secured, a threadedbayonet point pin with eyelet (not shown) is drilled into the femur 36until it reaches the far cortex 13. Next, the femur 36 is drilled usinga reamer 32. Ideally, a reamer should be used which is 9 or 10 mm wide,and the drilling should leave a femoral tunnel 10 which is 35 mm deep.Gradations along the reamer's shaft can be used to indicate the depth ofthe tunnel. Although some instruments described herein are notillustrated, all are commonly available and one of ordinary skill in theart will understand their use.

[0029] Once the femoral tunnel 10 has been drilled, a cross pin guide 38is attached directly to the reamer 32 and locked into place so that thecross pin guide 38 may rotate freely about the axis 37 of the femoraltunnel 10. As shown in FIG. 11, a tunnel locator 40 is mounted on thecross pin guide 38, and a ratcheting cannula 42 is inserted into thetunnel locator 40. Ideally, the cross pin guide 38 has graduations whichindicate the distance in millimeters from the tip of the reamer in thefemoral tunnel. Also ideally, the tunnel locator 40 is placed at the 15mm mark.

[0030] The ratcheting cannula 42 is advanced until it contacts the skin.The cross pin guide 38 is then rotated away and an incision is made downto the bone. The cross pin guide 38 is rotated back into position andthe ratcheting cannula 42 is advanced until it contacts the femoralcortex 13. A calibrated drill pin 12 is placed into the ratchetingcannula 42. Preferably, a 2.5 mm drill pin is used. The drill pin 12also is advanced until it contacts the femoral cortex 13. The drill pin12 is drilled into the femur 36 until it reaches the reamer 32, which isstill located in the femoral tunnel 10. Calibrated markings on drill pin12 allow the depth of penetration to be determined. The overall lengthof cross pin 20 and depth of the transverse tunnel 14 are determined byadding approximately 30 mm to the depth of penetration (reamer diameterplus 20 mm for the cross pin tip). The drill pin is then carefullywithdrawn about 5 mm from the reamer.

[0031] The cross pin guide 38 (including the tunnel locator 40) and thereamer 32 (along with a reamer pin if it is still in the femoral tunnel)are removed from the femur 36, and the drill pin 12 is gently tappeduntil it appears in the femoral tunnel 10. The appearance of the drillpin 12 can be seen through the use of an arthroscope which is placed inthe femoral tunnel 10. As it is advanced, the drill pin 12 should crossthe center of the femoral tunnel 10, so that it intersects with the axis37 of the femoral tunnel 10. If necessary, the reamer 32 is placed backinto the femoral tunnel 10, the cross pin guide 38 is reattached to thereamer 32, and placement of the drill pin 12 is repeated. The drill pin12 is then advanced into the medial side 25 of the femur 36, at least tothe depth as calculated above. Next, a cannulated cross pin reamer 16 isused to enlarge the lateral side 27 of transverse tunnel 14 forinsertion of the cross pin 20. Ideally, a soft tissue protector (notshown) is used in conjunction with the cross pin reamer 16.

[0032] Once the path has been enlarged, the drill pin 12 is withdrawnand a cross pin guidewire 18 is inserted through the cannulated crosspin reamer 16 and into the medial side 25 of the femur 36. With theguidewire 18 in place, the cross pin reamer 16 is removed and the crosspin 20 is advanced, distal end 31 first, over the guidewire 18, but notyet through the femoral tunnel 10. See FIG. 13. The guidewire 18 is thenwithdrawn from the femoral tunnel 10. Finally, the replacement ligament24 is looped onto the tendon passer 22 and inserted through the tibialtunnel 11 and on into the femoral tunnel 10. A surgical lubricant may beused to ease passage. Ideally, a tendon passer 22 with a T-handle (notshown) is used, so that when the T-handle is parallel with the cross pin20, the replacement ligament 24 is aligned such that further insertionof the cross pin 20 will capture the looped replacement ligament 24. Theguidewire 18 is inserted back across the femoral tunnel 10 into themedial side 25 of the femur 36, and the tendon passer 22 is removed. Atthis point, it is necessary to make sure that the replacement ligament24 has been captured over the guidewire 18. This can be done by gentlypulling on the ends of the replacement ligament.

[0033] The cross pin 20 can now be advanced over the guidewire 18,preferably using a cannulated driver (not shown). As the cross pin 20 isadvanced, the body 21 of the cross pin 20 acts to hold the replacementligament 24 against the wall 15 of femoral tunnel 10 and, thus, insurebetter ingrowth. Once fully seated, the body 21 also acts to secure thelooped replacement ligament 24 within the femoral tunnel. When the crosspin 20 can no longer be advanced, the cross pin 20 should be fullyseated. This resistance represents the second tapered portion 28engaging the medial wall 25 of the femoral tunnel 10. The guidewire 18may then be removed. Because of the gradual taper of the first taperedportion 26, the guidewire 18 is not essential, and its use may beomitted. Finally, the replacement ligament 24 is secured on the tibialside by any of various known fixation methods.

[0034] In the illustrated embodiment, the threaded portion 30 of theproximal end 29 of the cross pin 20 will bury into the femur 36 becausethe length has been custom determined for each patient. However, thecross pin 20 in accordance with the present invention is placed into thefemur 36 in such a position that the cross pin 20 may be retrieved fromthe femur 36 after the replacement ligament 24 has healed into the bone.It is understood that a cross pin 20 with a head 33 adjacent to thethreaded portion 30 will operate in the same manner. See FIG. 10. Also,the cross pin 20 used in the fixation system of the present inventionprovides high graft pull out values. Finally, the cross pin 20effectively attaches the replacement graft close to the anatomic originof the ACL on the femur 36.

[0035] Although the invention has been described with reference toseveral embodiments, variations and modifications exist within the scopeand spirit of the invention as described.

1. A pin for securing and positioning a replacement ligament in a bonetunnel of a receptor bone, the pin comprising: a distal end, a bodyportion, and a proximal end, a first tapered portion positioned at thedistal end, the first tapered portion extending toward the body portionand increasing in diameter closer to the body portion, a second taperedportion positioned between the first tapered portion and the bodyportion, the second tapered portion increasing in diameter closer to thebody portion, and a threaded portion at the proximal end, adjacent tothe body portion, the threaded portion for securing the pin within thereceptor bone.
 2. The pin of claim 1, wherein the first tapered portionhas an axially long, radially narrow taper, and the second taperedportion has an axially short, radially wide taper.
 3. The pin of claim2, wherein the body portion is substantially cylindrical.
 4. The pin ofclaim 1, further comprising a head, the head positioned at the proximalend, and the threaded portion positioned between the head and the bodyportion.
 5. The pin of claim 2, further comprising a head, the headpositioned at the proximal end, and the threaded portion positionedbetween the head and the body.
 6. A pin for securing and positioning areplacement ligament in a femoral bone tunnel of a receptor bone, thepin comprising: a distal end and a proximal end, a body portionextending between the distal end and the proximal end, the body portionproportioned and designed to secure the replacement ligament within thefemoral bone tunnel and to hold the replacement ligament in contact withthe receptor bone, a first tapered portion positioned at the distal end,the first tapered portion extending toward the body portion andincreasing in diameter closer to the body portion, the first taperedportion proportioned and designed to extend beyond the femoral bonetunnel and into the medial side of the femoral tunnel, a second taperedportion positioned between the first tapered portion and the bodyportion, the second tapered portion increasing in diameter closer to thebody portion, the second tapered portion proportioned and designed tourge the replacement ligament toward the receptor bone as the pin isinserted into the receptor bone and engage the medial side of thefemoral tunnel when the pin is inserted completely, and a threadedportion positioned at the proximal end, adjacent to the body portion,the threaded portion proportioned and designed to secure the pin withinthe receptor bone.
 7. The pin of claim 6 wherein the first taperedportion is axially long and has a taper which is radially narrow, andthe second tapered portion is axially short and has a taper which isgreater radially than the taper of the first tapered portion.
 8. The pinof claim 6, further comprising a head, the head being positioned at theproximal end, and the threaded portion being positioned between the headand the body portion.
 9. A pin for securing a replacement ligamentinside a tunnel of a receptor bone, the pin comprising: a body having adistal end and a proximal end, a threaded portion positioned at theproximal end, a first tapered portion positioned at the distal end, anda second tapered portion positioned adjacent to the first taperedportion, between the first tapered portion and the threaded portion butspaced from the threaded portion.
 10. The pin of claim 9 wherein thefirst tapered portion and the second tapered portion each have a distalend and a proximal end and increase radially from the distal end to theproximal end.
 11. The pin of claim 10 wherein the first tapered portionis axially relatively long, and the diameter of the first taperedportion increases gradually from the distal end to the proximal end. 12.The pin of claim 11 wherein the second tapered portion is axiallyrelatively short, and the diameter of the second tapered portionincreases rapidly from the distal end to the proximal end.
 13. The pinof claim 12 wherein the body is substantially cylindrical and has adiameter substantially equal to that of the proximal end of the secondtapered portion.
 14. A pin for securing a looped replacement ligamentinside a tunnel of a receptor bone of a patient, the pin comprising: abody having a distal end and a proximal end, the body including meansfor engaging the receptor bone to anchor the pin in the receptor bone,such means being positioned at the proximal end, means for securing thelooped replacement ligament in the receptor bone, means for holding thelooped replacement ligament in contact with the receptor bone, means forproviding resistance when the pin is inserted fully within the receptorbone, and means for inserting the pin through the looped replacementligament and into the medial side of the receptor bone, such means beingpositioned at the distal end.